Outside, They Look Like Completely Normal Townhouses. Inside, They're Hiding An Interesting History

If you pass by 58 Joralemon Street in Brookyln Heights, you might not notice anything out of the ordinary. Its windows are blacked out and it's very quiet, as though nobody lived in the brownstone at all.

In fact, the brownstone isn't a townhouse at all. It's nine stories above the NYC subway tracks for the 4 and 5 lines. If you could peek into the front door, you'd see concrete flooring and a bunker door leading to a cave.

The property was once a real residence that dated all the way back to 1847 but in 1908, with the construction of the first underwater subway tunnel to connect Brooklyn and Manhattan, the Metropolitan Transportation Authority (MTA) acquired the home to be used as a subway ventilator.

In the 1990s, the MTA cleaned it up and offered the neighbors use of the garden space. The property got winding vines, and in 1999 the historic facade was fully restored, with the former unsightly ventilation grates put up on the roof.

In case you're wondering, the real estate value of this empty ventilation facade brownstone? $2.8 million. Only in New York.

A neighbor lucky enough to get a tour of 58 Joralemon Street described it as “something out of A Clockwork Orange… it was open and cavernous, with catwalks going back and forth, this way and that, and somewhere down below the trains going by.”

Post-9/11, the property was updated to be used as an emergency exit for MTA workers in the event of a subway fire, flood or gas crisis. The subway workers would simply exit out of the brownstone doors to safety on a tree-lined Brooklyn street.

But New York isn't the only city with a fake townhouse. In London's Bayswater, a residential street in a high-end neighborhood masks another portal to the London Underground.

It was constructed in the 1860s when the line between Paddington and Bayswater was built. The path ran directly under 23 and 24 Leinster Gardens. The two homes were purchased by the city and demolished. But after they were razed, the two townhouses emerged again, this time, as five-foot facades to disguise the large hole left by construction as ventilation. The old train was initially powered by steam, so ventilation was key. Today, you can still see the trains behind the facade.

In his novel “Foucault's Pendulum”, Umberto Eco writes about a fake house in Paris: “[People] walk by and they don’t know the truth that the house is a fake. It’s a facade, an enclosure with no room, no interior. It is really a chimney, a ventilation flue that serves to release the vapors of the regional Métro. And once you know this you feel you are standing at the mouth of the underworld…”

The house is located at 145 Rue la Fayette in the 10th arrondissement.

“The building 145, rue la Fayette is only a front. Literally. The balcony is there, the door is there, but no building waits behind it. The false facade is there only to hide a giant ventilation chimney for the metro,” the blogger behind Paris by Cellphone writes.

On the Rue du Temple and Rue Chapon in the Marais, you can see a similar secret passageway on the Paris metro that's actually nothing more than an artist's trompe l'oeil.

The facade was created by artist Julien Berthier. It takes up 10cm of public space, but years later, the city still recognizes the fake door as a real address. City services are quick to clean off any graffiti and preserve the tromp l'oeil.